The present invention relates to interframe coding techniques for video signals.
Video signals contain much redundant information, both within each frame and between successive frames. Numerous video signal coding techniques known in the art exploit these intraframe and interframe redundancies so as to reduce the amount of information needed to describe the video image.
In particular, interframe coding techniques generally involve comparing a current frame to that which preceded it and determining the differences between them. These differences are then what is encoded for transmission. This approach typically requires the transmitting station to include a one-frame delay element or "frame memory" so that the interframe comparisons can be made. Reconstruction, or decoding, of each frame at the receiving station also requires a frame memory, with the received encoded differences from one frame being combined with the reconstructed previous frame, stored in the frame memory, so as to reconstruct the current frame. Disadvantageously, the high cost of frame memories capable of storing entire video frames is, in general, a substantial deterrent to viable commercial implementation of interframe coding techniques heretofore known.